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1.
The serum immunoglobulin concentrations in two-day-old Finnish x Dorset Horn lambs, which were born and nursed indoors, were high and unrelated to littersize, except when young ewes had large litters, or when ewes lambed twice in a year. The results contrast sharply with those from Merino and Blackface lambs, examined previously, whose mean concentrations were much lower, and generally fell substantially with increasing litter-size. The superiority of the Finnish x Dorset Horn sheep in this respect is attributed to the ability of the lambs to suck particularly vigorously, shortly after birth, especially when large litters are compared, and to a higher rate of colostrum production by the ewes. The correlations between the immunoglobulin concentrations in the lambs and their growth and survival were significant but slight.  相似文献   

2.
Twin-bearing Targhee ewes (Exp. 1, 1 yr, n = 42) and 1,182 single- and twin-bearing whiteface range ewes (Exp. 2, n = 8 experimental units over 2 yr) were used in a 2 x 2 factorial arrangement of treatments to determine the effect of supplemental energy source and level of vitamin E supplement on lamb serum metabolites and thermogenesis (Exp. 1) and on lamb growth (Exp. 2). During late gestation, ewes were individually fed (Exp. 1) or group-fed (Exp. 2) a daily supplement. Supplements were 226 g/ewe of daily safflower seed (DM basis; SS) with either 350 IU/ewe daily (VE) or no added supplemental (VC) vitamin E; or 340 g/ewe daily of a barley-based grain supplement (DM basis; GC) and either VE or VC. One hour postpartum in Exp. 1, twin-born lambs were placed in a 0 degrees C dry cold chamber for 30 min. Lamb rectal temperature was recorded every 60 s and blood samples were taken immediately before and after cold exposure. In Exp. 2, lambs were weighed at birth, at turnout from confinement to spring range (32 d of age +/- 7; turnout), and at weaning (120 d of age +/- 7). Ewes were weighed at turnout and weaning. In Exp. 1, a level of vitamin E x energy source interaction was detected (P < 0.10) for body temperature and change in NEFA and glucose concentrations. Lambs from SSVC ewes had the lowest (P = 0.01) body temperature and had decreased (P = 0.08) NEFA concentration. The SS lambs tended to have decreased (P < 0.11) concentrations of blood urea N (BUN) and thyroxine at 0 min than did lambs born to GC ewes. After 30 min of cold exposure, SS lambs had increased and GC lambs had decreased BUN, triiodothyronine, and triiodothyronine:thyroxine concentrations (P < 0.10). In Exp. 2, kilograms of lamb per ewe at turnout and weaning and lamb survival at weaning were greater (P < 0.07) for GC than SS lambs. Based on the decreased body temperature in SSVC lambs at birth, the greater change in BUN during the cold exposure for SS than GC lambs, and the decreased survival rate for SS than GC lambs, SSVC-supplemented ewes appeared to give birth to lambs with an apparently decreased energetic capacity. This may compromise the ability of the newborn lamb to adapt to extreme environmental conditions.  相似文献   

3.
The frequency of human intervention during lambing was assessed for 708 lambs and 162 ewes in up to four deliveries. In total, 21.8 per cent of the lambs born alive required some assistance at birth and 9.4 per cent were delivered manually. Assistance was required less frequently by twin lambs and ewe lambs, and Scottish blackface lambs required assistance less frequently than Suffolk lambs. Approximately one-third of the ewes were assisted in at least one delivery and 10 per cent were assisted in all their deliveries; however, less than 20 per cent of ewes were assisted more than once. A quarter of the lambs needed some human intervention to suck successfully, and Suffolk lambs needed help more frequently. The lambs born to almost half the first-parity ewes needed help to suck, but at later deliveries the lambs born to less than a third of the ewes needed assistance. In blackface flocks the survival of 100 lambs required 4.6 hours of human intervention whereas in Suffolk flocks 28 hours were required.  相似文献   

4.
Milk production and lamb growth were characterized in 118 multiparous, 3- to 7-yr-old Rambouillet, Columbia, Polypay, and Suffolk ewes under spring sage range and high mountain meadow grazing from 28 to 98 d postpartum. Daily milk yield as measured by the lamb suckling weight differential technique did not differ (P greater than .05) among breeds, although milk production of Suffolk ewes tended to be higher than that of the other three breeds. Within the Rambouillet, Columbia, and Polypay breeds, total estimated yield of ewes with twins was 13 to 17% higher than that of ewes with singles, whereas in the Suffolk breed, suckling twins increased total milk yield 61% over that of ewes with singles. Twin lambs induced a larger differential in dam milk production in late lactation (70 to 98 d) than in earlier lactation (28 to 70 d). Number of lambs did not influence milk protein, Ca, or P content (P greater than .05). Fat levels in colostrum and 4-d milk were elevated 14 and 20%, respectively, in ewes suckling twins compared with ewes suckling singles. Under range conditions, Suffolk ewes suckling single or twin lambs lost more BW (12 and 21% of 4-d postpartum body weight, respectively) than Rambouillet (4 and 7%), Columbia (5 and 8%), or Polypay (8 and 8%) ewes. Correlation coefficients of milk production and lamb growth rate were positive and significant (P less than .05) up to 56 d of age. Growth rate was less closely associated with milk production for twin than for single lambs.  相似文献   

5.
Pure-bred embryos were transferred within and reciprocally between large (Suffolk) and small (Cheviot) breeds of sheep to establish 4 treatment groups: SinS (Suffolk embryos in Suffolk dams), SinC (Suffolk embryos in Cheviot dams), CinS (Cheviot embryos in Suffolk dams), and CinC (Cheviot embryos in Cheviot dams). The recipient ewes carried single fetuses to term. The maternal plasma concentrations of ovine placental lactogen (oPL), progesterone, IGF-1, FFA, and glucose were measured on d 50, 90, 120, and 140 of pregnancy. Birth weight, body dimensions, and placental characteristics of lambs were recorded at birth. There was a recipient ewe breed × lamb breed × time interaction for the concentration of oPL (P = 0.03), but no such interaction was observed for progesterone (P = 0.42), IGF-1 (P = 0.57), glucose (P = 0.36), or FFA (P = 0.72). There were no differences in oPL (P = 0.28) and progesterone (P = 0.34) concentrations between SinC and SinS ewes. The concentrations of FFA on d 140 (P = 0.008), and those of glucose on d 50 (P = 0.02) and 120 (P = 0.01), were greater in SinC ewes than in SinS ewes. The ewes in CinS had less FFA concentration (P = 0.002) at all time points than CinC ewes. The concentrations of IGF-1 on d 90 were greater (P = 0.004) in CinS ewes than CinC ewes, but did not differ (P = 0.16) on d 50, 120, and 140. The concentrations of glucose on d 50 (P = 0.001), 90 (P = 0.03), and 140 (P = 0.03) were less in CinS ewes compared with CinC ewes. The birth weight of SinC lambs (5.04 ± 0.20 kg) was lighter (P = 0.001) than SinS lambs (5.94 ± 0.19 kg), and body dimensions of SinC lambs were smaller (P = 0.01) than SinS lambs. Neither birth weight nor the body dimensions of CinS lambs differed (P = 0.24) from CinC lambs. Cotyledon number was reduced (P = 0.04) in the CinS (57.5 ± 6.3) compared with the SinS group (74.2 ± 5.9), whereas mean cotyledon weight in CinS (2.42 ± 0.20 g) was greater (P = 0.02) than SinS (1.74 ± 0.21 g). It was concluded that the large genotype lambs were lighter and smaller when born to small genotype dams; however, the birth weight or body dimensions of small genotype lambs did not differ when born to large genotype dams. This study suggests that plasma oPL, progesterone, IGF-1, FFA, and glucose concentrations at different times throughout pregnancy reflect the regulatory effect of the uterine environment on the development of the fetus.  相似文献   

6.
Observations of behaviour at parturition of prolific Booroola Merinos were recorded for 48 single-, 77 twin-, 56 triplet- and 14 quadruplet-bearing ewes. Average lamb birthweight decreased as litter size increased. Single lambs were on average 2 kg heavier than quadruplet lambs. Within twin and triplet litters the period of abdominal straining during labour was significantly shorter for later-born lambs than for the first-born lamb. Single-born lambs were presented longer at the ewe's vulva than lambs from other litters. The first-born of twins was presented longer at the ewe's vulva than the second-born lamb. Ewes 2 years of age were slower to stand after birth and to begin to groom lambs than adult ewes. The ewe was not selective in grooming members of a litter. The first-born lamb of single and twin litter sizes was quicker to stand and suck than the first-born lamb of triplet and quadruplet litters. The second-born lamb of twins was quicker to suck than the second-born of other litter sizes. Birth order did not affect the time taken to suck. Regardless of litter size, heavier lambs were quicker to stand and suck resulting in a greater chance of survival, and an increase of 1 kg in birthweight resulted in a 28% increase in survival. Survival of lambs was significantly affected by their behaviour after adjustment for birthweight. With an increase of 1 min in the intervals from delivery to when the lamb first attempts to stand, stands or attempts to find the udder its chances of survival decreased by about 1%. It was concluded that birthweight was the major component affecting lamb survival in prolific Booroola Merino sheep.  相似文献   

7.
Limited information is available on differences between sheep breeds with respect to helminth resistance under temperate conditions. The present study was designed to confirm and extend preliminary findings on observed breed differences in resistance to naturally acquired gastrointestinal nematodes in Suffolk and Texel sheep. Three trials were carried out. In trial 1 (1999-2003) lambs co-grazed from birth were faecal sampled at various time points up to 17 weeks of age. Worm burden was assessed at 17 weeks of age from a minimum of six lambs per breed in each of the 3 years. In trial 2, faecal egg count (FEC) was determined on six farms with co-grazed Suffolk and Texel purebred lambs. In trial 3 (2001-2003), ewes were faecal sampled at winter housing. In all three trials, an influence of breed on resistance to naturally acquired trichostrongyle infection was demonstrated. In trial 1, significantly higher FEC and worm burden was observed in Suffolk compared with Texel lambs following natural challenge. In trial 2, FEC recorded in lambs from six farms confirmed the breed differences previously observed. A breed difference in resistance to GI parasites was also observed in older ewes. In both breeds, an age effect on the FEC was observed with younger ewes having greater FEC than older ewes.  相似文献   

8.
External pelvic measurements were made in 837 adult ewes of 21 different breeds, the majority of which were rare breeds. The pelvic measurements were the intertuber coxal diameter, the distance between the lateral tuber ischii and medial tuber ischii and the rump length. There was a considerable breed variation with the Soay ewes having the smallest and the Suffolk the largest pelvic dimensions. However when the relationship between pelvic size and ewe's bodyweight was compared, the ratio of the medial tuber ischii:bodyweight and sum of four pelvic dimensions:bodyweight of the Soay was over twice that of the Suffolk ewes. When the size of the pelvis was related to the lamb's birth weight the Soay's was relatively larger. Dystocia caused by feto-maternal disproportion occurred in 19 ewes, all with singletons. In 16 cases involving four different breeds the birth weights of the lambs were significantly larger than those lambs which were born normally.  相似文献   

9.
Multiparous Suffolk and Suffolk-cross ewes were randomly allotted to treatments within breed and year to measure effects of ram exposure, during transition from anestrus to breeding activity, on reproductive performance. Treatments were: 1) ewes joined with two mature vasectomized Rambouillet rams for 15 d before breeding (DC), 2) ewes maintained across a net wire fence from two vasectomized rams for 15 d before breeding (FC) and 3) ewes maintained approximately 400 m away from rams (NC). At the end of the 15 d, all ewes were placed in one pasture and mated to three fertile Suffolk rams during a 34-d breeding season. A total of 96 Suffolk and 177 Suffolk-cross ewes was utilized during the 3-yr experiment. A greater (P less than .05) prebreeding ovulation percentage was observed in DC and FC than in NC ewes. Mating and lambing occurred approximately 6 d earlier for DC or FC ewes than for NC ewes. A similarly designed experiment was conducted using Suffolk and Suffolk-cross ewe lambs allotted to treatments within breed and year to measure effects of ram exposure during the natural breeding season, but prior to breeding. Treatment differences were not detected (P greater than .05) for date of first observed estrus, date of lambing, percentage of ewes lambing in the first 17 d of the lambing season, number of lambs born per ewe lamb exposed or number of lambs born per ewe lamb giving birth.  相似文献   

10.
Pregnant ewes were supplemented with dl-alpha-tocopheryl acetate, either as a single intramuscular dose (500 mg two weeks before lambing) or perorally (150 mg daily during 3-4 weeks before lambing). Ewes without such a supplementation were controls. The vitamin E supplemented ewes had nearly twice as high vitamin E (alpha-tocopherol) concentrations as the unsupplemented control ewes at lambing both in serum and in colostrum. The vitamin E concentration in colostrum was 5-11 higher than in milk 1 week after lambing. Both supplementations somewhat increased the vitamin E serum concentration of the newborn lambs, but the increase was negligible in comparison with the effect produced by the consumption of colostrum. All lambs had very low serum concentrations at birth. The lambs from the supplemented ewes had significantly higher serum values than the control lambs 24 h after birth. The ewes had somewhat higher selenium status at birth than their offsprings when evaluated by glutathione peroxidase (GSH-Px) in the erythrocytes. It seems reasonable that nutritional muscular degeneration may arise in newborn lambs with a normal selenium status if their vitamin E status is critical, either because of an inadequate consumption of colostrum or because of a vitamin E deficient diet during pregnancy with a low vitamin concentration of colostrum as a consequence.  相似文献   

11.
Ewes carrying twin fetuses were maintained during late pregnancy on a uniformly high plane (n = 22), a uniformly low plane (LP) (n = 24) or a low plane increasing to a high plane (n = 14) of nutrition. Seven ewes at each nutritional level were killed at 142 days of gestation and the liver and muscle glycogen and body lipid concentrations of the fetuses were determined. The rest of the ewes lambed naturally at about 145 days and the colostrum yields were obtained by hand milking after oxytocin injections during the first 18 hours after birth. The lactose, lipid and protein concentrations of colostrum were determined. Undernutrition in the LP group did not apparently affect the body concentrations of available glycogen, reduced available body lipid by about 47 per cent and reduced the lactose, lipid and protein available in colostrum during the first 18 hours by about 50 per cent. Refeeding previously underfed ewes to a high plane during the last five to 10 days of pregnancy did not improve the available reserves of glycogen or lipid in the lambs but did increase the yields of colostral constituents by about 30 per cent. The relative contributions of body reserves and colostral constituents to the maintenance of high, medium and low metabolic rates in lambs from different groups was assessed. It was concluded that under normal field conditions refeeding undernourished ewes during the last weeks of pregnancy would improve only marginally the survival potential of the lambs and that most lambs would be compelled to draw on their body glycogen reserves in order to maintain heat production during the first 18 hours after birth, even when they consumed all the available colostrum.  相似文献   

12.
Neonatal lamb mortality is a major factor affecting profitability in the sheep industry, and lamb thermogenesis is a key element in neonatal lamb survival. Increased lamb vigor has been reported when ewes were supplemented during late gestation with algae-derived docosahexaenoic acid (DHA); however, the effects of DHA on lamb thermogenesis and immunocompetence have not been investigated. Eighty twin-bearing Targhee ewes (ages 2 to 5 yr; 68.5 ± 3 kg) were assigned randomly to 1 of 2 supplement treatments to determine the effects of feeding DHA to ewes during late gestation and early lactation on lamb thermogenesis, serum metabolites and hormones, and lamb growth. Supplement treatments were 12 g·ewe(-1)·d(-1) of algae-derived DHA (DHA Gold Advanced Bionutrition Corp., Columbia, MD; algae-derived DHA); and no algae-derived DHA (control). Supplements were individually fed daily during the last 30 d (±7 d) of gestation and pen fed (6 pens/treatment with 6 or 7 ewes/pen) during the first 38 d (±7 d) of lactation. One hour after lambing and before nursing, twin-born lambs were weighed, blood sampled via jugular puncture, and placed in a dry cold chamber for 30 min (0°C), and rectal temperatures were recorded every minute for 30 min. Lambs were removed from the cold chamber, blood sampled, warmed for 15 min, and returned to their dam. Ewes were blood sampled, and colostrum samples were collected 1 h postpartum. Ewe and lamb sera were assayed for glucose, NEFA, cortisol, and leptin. Lamb rectal temperature, glucose, NEFA, cortisol, leptin, and birth weights did not differ between treatments. The BW at 38 d was greater (P = 0.03) for lambs born to control ewes than for lambs born to algae-derived DHA-supplemented ewes; however, the colostrum of algae-derived DHA-supplemented ewes had a greater specific gravity (P = 0.05) than for control ewes. Overall, despite a potentially positive effect on ewe colostral IgG concentrations, supplementation of algae-derived DHA during late gestation and early lactation had a negative effect on lamb BW and did not affect indices of lamb thermogenesis.  相似文献   

13.
The birth and fate of 818 lambs born to 571 ewes on a low-ground farm in the Scottish Borders with a history of substantial perinatal mortality were monitored with a range of physiological, biochemical and pathological measurements. In lambs which survived, the rectal temperature, birthweight and plasma concentrations of fructose, insulin, thyroxine and the third component of complement at birth, and the weight at four months of age, decreased with litter size. One hundred and thirty-seven lambs were stillborn or died within four days and seven others died later. The mothers of 77 per cent of these lambs had low condition scores, but the lamb deaths did not correlate significantly with the condition scores. From data relating to birthweight, temperature, packed cell volume and plasma composition it was deduced that placental insufficiency was involved in 24 per cent of these deaths; acute hypoxaemia at birth accounted for 35 per cent, inadequate thermogenesis for 12 per cent and starvation for 13 per cent. The remaining 16 per cent of dead lambs could not be assigned to any of these categories. Using only clinicopathological criteria, 37 per cent of the lamb deaths were attributed to antenatal influences which included immaturity, developmental anomalies, and degenerative or inflammatory changes. Thirty-three per cent of the deaths were due to post natal factors which included, in declining order of frequency, starvation, enteritis, misadventure, pneumonia, navel infections and septicaemia. No conclusions could be drawn from the pathological examinations alone in the remaining 30 per cent, although almost half of these had low rectal temperatures after birth, death being attributed to hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

14.
A terminal sire Composite population was formed by mating Columbia rams to Hampshire-Suffolk crossbred ewes. Subsequent generations were produced by inter se mating. The objective was to compare Composite sheep to purebred Suffolks for numerous performance traits. Young ewes lambing at 1 yr of age were evaluated separately from mature ewes (2, 3, 4, and 5 yr old) of each population. Composite and Suffolk populations did not differ significantly in components of litter weaning weight per young ewe joined. Mature Composite ewes produced more wool than Suffolk ewes. Fertility of mature ewes did not differ significantly between populations. The greater prolificacy (P less than .01) of mature Suffolk ewes was offset by a lower survival to weaning (P less than .01), particularly for twin-born lambs. Consequently, mature Composite and Suffolk ewes did not differ for number weaned and litter weaning weight per ewe joined. The average birth weight of lambs born to young and mature Composite ewes was greater (P less than .02) than the average birth weight of Suffolk lambs. The average weaning weight of lambs born to young Composite ewes was greater (P less than .05) than that of lambs born to young Suffolk ewes. Breed differences were not detected for preweaning daily gains, weaning weights, and postweaning daily gains of ewe lambs born to mature ewes. Likewise, weights of ewes at 125 d of age and weights of mature ewes at breeding did not differ significantly between breeds.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
A total of 399 crossbred ewes born in 2 yr were maintained either on irrigated or dryland hill pastures. The ewes were sired by North Country Cheviot, Dorset, Finnsheep or Romney rams mated to Suffolk or Columbia-type ewes. The crossbred ewes were mated to Hampshire rams throughout the study and had the opportunity for either 4 or 5 yr of production. Annual feed cost was calculated based upon estimated annual metabolizable energy (ME) requirements for maintenance, ewe growth, pregnancy and lactation. Income from weaned feeder lambs and from orphan lambs sold shortly after birth, feed cost and net revenue were analyzed during each ewe's first production year, as well as for the entire period of the experiment. Crossbred group significantly affected income from lambs produced, feed cost and net revenue for the ewes' first production year. Crossbred group and crossbred group X management system interactions generally influenced lifetime income from lambs produced and from orphans sold, gross income, total cost and net revenue per ewe. Finnsheep X Suffolk ewes performed best on irrigated pastures but were below average for lifetime net revenue on hill pastures. Finnsheep X Columbia ewes performed best on hill pastures and, with Dorset X Suffolk and Dorset X Columbia ewes, were well above average for lifetime net revenue on irrigated pastures as well. Suffolk crossbreds consistently performed better on irrigated than on hill pastures. While most ewes with Columbia-type inheritance were more efficient on hill than on irrigated pastures, this result was not always consistent.  相似文献   

16.
试验对萨福克羔羊0~65日龄生长发育规律进行了分析,旨在完善肉羊的生长发育规律研究,为萨福克羔羊0~65日龄的饲养管理及营养水平提供理论依据。试验于新疆华兴牧场惠康畜牧种羊繁育基地进行,供体母羊为纯种萨福克羊,受体母羊为哈萨克羊,并对出生的萨福克羔羊进行体尺、体重测量和记录,将数据输入Excel表格进行整理,并通过SPSS 16.0软件分析各性状平均值和各个体尺指标与体重平均值的相关性。结果表明,0~30日龄萨福克羊生长发育速度相对较快,公羔臀宽与体重的相关系数为0.989;管围与体重的相关系数为0.638;母羔臀宽与体重的相关系数为0.981,管围与体重的相关系数为0.654。0~30日龄萨福克羊公羔各性状的生长发育比母羔快,45~65日龄生长速度一致。羔羊0~15日龄体高、体长、胸围和体重等生长速度最快,而30~65日龄体高、体长、体重等部位生长速度较平稳;由体尺、体重相关性分析可知,臀宽与体重相关系数最大,管围和体重相关系数最小。由研究可知,0~30日龄营养要求关键,公羔与母羔的生长发育无明显差异,欲提高羔羊的生长发育速度则要注意羔羊各年龄阶段的生长发育规律,合理提供营养并提高饲料质量与管理水平。今后对萨福克羔羊的饲料管理中应该注重不同时期的饲养配方,合理改善饲养环境,使其发挥最大生长潜能。  相似文献   

17.
The objective of this study was to compare reproductive efficiency and wool production of 1/4 Finn crossbred ewes with straightbred Columbia, Rambouillet and Targhee ewes. In Phase I, white-faces ewes (WF; Columbia, Rambouillet and Targhee) were bred to either rams of their own breed or Finnish Landrace X Rambouillet rams (F X R) to produce 821 lambs from 563 lambings. Ewes bred to F X R had similar average litter size and individual lamb weights at birth, 60 d and weaning as those bred to WF. Lambs sired by F X R had 7% higher (P less than .01) lamb weaned per ewe lambing for ewes bred to F X R rams. For Phase II, approximately equal numbers of F X R-sired (1/4Fx) and WF-sired female lambs produced in Phase I each year were exposed to Suffolk rams at yearly intervals beginning at 7 mo of age. At 1 yr of age, 1/4Fx had higher fertility (P less than .01) than WF (37.7% vs 1.3%), resulting in 14.0 kg more lamb weaned per ewe exposed to breeding. Mature (ages 2 to 6 yr) 1/4Fx ewes had similar fertility to mature WF ewes, but litter size, number of lambs at 60 d and weaning was .36, .24 and .22 lambs higher (P less than .01), respectively, for mature 1/4Fx. Progeny of 1/4Fx were lighter at birth (P less than .01), but not different (P greater than .05) at 60 d and weaning than those of WF. Survival to 60 d unadjusted and adjusted for birth weight was 4.6% (P less than .05) and 7.6% (P less than .01) higher, respectively, for 1/4Fx progeny than for WF progeny.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

18.
Intrauterine transmission of ovine progressive pneumonia virus   总被引：2，自引：0，他引：2  
Ovine fetuses, newborn lambs, and ovine colostrum were examined for ovine progressive pneumonia virus. The lambs and colostrum were also examined for specific antibody. Virus was isolated from 1 fetus, from 2 newborn lambs, and from most samples of colostrum. The fetus was about 100 days old and was carried by a seronegative ewe in contact with seropositive sheep. Both newborn lambs were carried by seropositive ewes. One lamb was dead at birth; the other lamb was normal and had not nursed. Antibody specific for the virus was present in the colostrum of 12 of 14 seropositive ewes and in the serum of 8 of 11 lambs that had nursed seropositive ewes, but not in the serum of lambs that had not nursed.  相似文献   

19.
Maedi-visna virus (MVV) seroprevalence associated with consumption of colostrum from seropositive ewes was investigated in 276 housed lambs from birth to 300 days-old. At birth, lambs were allocated to five experimental groups according to the maternal MVV-serological status, source and mode of feeding colostrum (bovine or ovine and bottle fed or suckled from the dam) and type of horizontal MVV-exposure (raised with the dam or separately with other lambs). The risk of being seropositive at 300 days-old was associated with feeding ovine colostrum from seropositive ewes and increased with intake of bottle-fed ovine colostrum and was higher in lambs separated from their dams and raised with other experimental lambs compared to lambs raised with their dams. Approximately 75-87% of ELISA-positive results in lambs that had ovine colostrum was attributable to colostrum itself. However, approximately only 16% of naturally raised and 29-61% of bottle-fed ovine colostrum lambs were ELISA-positive as a result feeding ovine colostrum. These results confirm that ovine colostrum from seropositive ewes can be a major source of MVV but its overall contribution to seroprevalence in natural conditions is relatively low, and shows that horizontal MVV transmission can be an important source of infection in new-born lambs.  相似文献   

20.
Sixty ewe lambs, 12 each of Suffolk, Dorset, Finnish Landrace, Finn-Dorset and Rambouillet born in January and February were used in a study of puberty and duration of the first breeding season. Ovulation was monitored via progesterone assay of weekly blood samples beginning in July, and estrus via daily checking with vasectomized rams. All 60 ewes ovulated but three, one Dorset and two Rambouillet failed to show estrus although each had five to seven ovulatory cycles. Several ewes showed small progesterone rises, 300 to 500 pg/ml, before first ovulation and six (10%) failed to initiate regular cyclicity following the first ovulation as defined by progesterone greater than 500 pg/ml. Mean number of ovulatory events before the first behavioral estrus ranged from 1.25 for Finnish Landrace to 2.20 for Rambouillet ewe lambs (P less than .1). Rambouillets were older (277 d; P less than .05) at first estrus than Finns (258 d) and Finn-Dorsets (260 d), but differences in age at first ovulation were not significant: Finn-Dorset, 233 d; Dorset, 234 d; Finn, 235 d; Rambouillet, 240 d; Suffolk, 245 d. Most cycles were of normal length, with 91.4% between 14 and 20 d. Repeatability of cycle length within breed group was .38. Suffolks had significantly shorter cycles (16.1 d) than the other four groups (17.0 to 17.4 d). Finnish Landrace and Finn-Dorset ewes continued to cycle much longer than the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

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